Saturday night palsy - radial nerve mononeuropathy due to improper arm positioning associated with inebriated sleep.
Physical examination - Wrist and finger drop.
Patients may have findings suggestive of ulnar nerve co-involvement (interossei testing) which may falsely lead the examiner to consider a more proximal location for the lesion such as the brachial plexus.
The finger drop caused by the radial nerve lesion places the hand at a mechanical disadvantage. Adjust for this by examining the hand on a flat surface (stretcher, counter top). With the fingers now supported in extension at the MCP joint (no longer "dropped"), the interossei can now be tested in isolation and will be normal.
